This patent relates to a system for mixing a system of at least two components. In particular, this patent relates to a system for mixing and dispensing an at least two-component system.
In the medical field, due to long or medium term stability issues or interaction between two components, two components may need to be mixed or reconstituted shortly before administration to the patient. This mixing must be done to a degree which causes the desired solution to be formed and also will likely need to be done in a sterile environment. These two components may take several forms such as of a lyophilisate and a solvent or diluent, a liquid and a liquid, a powder and a liquid or a pair of components with one or both being frozen.
More particularly in the field of tissue sealants used to seal or repair biological tissue, a sealant is typically formed from two or more components that, when mixed, form a sealant having sufficient adhesion for a desired application, such as to seal or repair skin or other tissue. Such sealant components are preferably biocompatible, and can be absorbed by the body, or are otherwise harmless to the body, so that they do not require later removal.
For example, fibrin is a well known tissue sealant that is made from a combination of at least two primary components—fibrinogen and thrombin. Fibrinogen is used as the substrate, while thrombin is used as the catalyst, cleaving fibrinopeptides A and B to form a fibrin network. Fibrinogen and thrombin have, depending on the temperature, viscosities of about 90-300 cps and 5 cps, respectively. Upon coming into contact with each other, the fibrinogen and thrombin components interact to form the tissue sealant fibrin, which is extremely viscous.
The fibrinogen and thrombin components are typically kept in separate containers so as to be combined only just prior to application. However, because fibrinogen and thrombin have different viscosities, a complete and thorough mixing is often difficult to achieve. If the components are inadequately mixed, then the efficacy of the sealant to seal or bind tissue at the working surface may be compromised.
To overcome the difficulties of the formation of the highly viscous fibrin in the medical field, in providing tissue sealant, it has become common to provide in-line mixing of the two or more components—in lieu of batch or tank mixing of the components. Some sealant products that may provide suitable mixtures include FLOSEAL, COSEAL, TISSEEL and ARTISS sealants from Baxter Healthcare Corporation, OMINEX sealants from Johnson & Johnson and BIOGLUE sealants from Cryolife, Inc. Such sealant may be applied by a dispenser that ejects sealant directly onto the tissue or other substrate or working surface. Examples of tissue sealant dispensers are shown in U.S. Pat. Nos. 4,631,055, 4,846,405, 5,116,315, 5,582,596, 5,665,067, 5,989,215, 6,461,361 and 6,585,696, 6,620,125 and 6,802,822 and PCT Publication No. WO 96/39212, all of which are incorporated herein by reference. Further examples of such dispensers also are sold under the TISSOMAT and DUPLOJECT trademarks, which are marketed by Baxter AG. Typically, in these prior art devices, two individual streams of the components fibrinogen and thrombin are combined and the combined stream is dispensed to the work surface. Combining the streams of fibrinogen and thrombin initiates the reaction that results in the formation of the fibrin sealant.
While thorough mixing is important to fibrin formation, fouling or clogging of the dispenser tip may interfere with proper dispensing of fibrin. Such clogging or fouling may result from contact or mixing of the sealant components in a dispenser for an extended period of time prior to ejection of the sealant components from the dispensing tip. Further, the quality of mixing of the two or more components having different viscosities may vary depending on the flow rate. For example, under certain flow conditions, the components may be dispensed as a less than thoroughly mixed stream.
Frankly, inadequate mixing of the type described above is also a problem present in other medical and/or non-medical fields, where two or more components having relatively different viscosities are required to be mixed together. Such components may tend to separate from each other prior to use or be dispensed in a less than thoroughly mixed stream, due at least in part to their different viscosities, flow rates and depending on the temperature and amount of time such mixture may be stored prior to use.
Inadequate mixing may also result in un-dissolved granules which may clog downstream passageways or result in a solution that is ill suited for the application in for which the solution is intended.
Accordingly, although prior devices have functioned to various degrees in forming and dispensing mixtures, there is a continuing need to provide a mixing and dispensing system that provides reliable and thorough mixing of at least two components (such as, for example, for a tissue sealant) for application to a desired work surface or other use applications in other fields. Further, there is a desire to provide a mixing system that is not dependent on the flow rate to achieve sufficient mixing.
As set forth in more detail below, the present disclosure sets forth an improved assembly embodying advantageous alternatives to the conventional devices and approaches discussed above.